for the sponge
- 50 grams walnut pieces
- 225 grams caster sugar
- 225 grams soft unsalted butter (plus some for greasing)
- 200 grams plain flour
- 4 teaspoons instant espresso powder
- 2½ teaspoons baking powder
- ½ teaspoon bicarbonate of soda
- 4 large eggs
- 1 - 2 tablespoons milk
for the frosting
- 350 grams icing sugar
- 175 grams soft unsalted butter
- 2½ teaspoons instant espresso powder (dissolved in 1 tablespoon boiling water)
- approx. 10 walnut halves (to decorate)
- Preheat the oven to 180°C/160°C Fan/gas mark 4/350°F.
- Butter two 20cm / 8inch sandwich tins and line the base of each with baking parchment.
- Put the walnut pieces and sugar into a food processor and blitz to a fine nutty powder.
- Add the 225g/2 sticks butter, flour, 4 teaspoons espresso powder, baking powder, bicarb and eggs and process to a smooth batter.
- Add the milk, pouring it down the funnel with the motor still running, or just pulsing, to loosen the cake mixture: it should be a soft, dropping consistency, so add more milk if you need to. (If you are making this by hand, bash the nuts to a rubbly powder with a rolling pin and mix with the dry ingredients; then cream the butter and sugar together, and beat in some dry ingredients and eggs alternately and, finally, the milk.)
- Divide the mixture between the 2 lined tins and bake in the oven for 25 minutes, or until the sponge has risen and feels springy to the touch.
- Cool the cakes in their tins on a wire rack for about 10 minutes, before turning them out onto the rack and peeling off the baking parchment.
- When the sponges are cool, you can make the buttercream.
- Pulse the icing sugar in the food processor until it is lump free, then add the butter and process to make a smooth icing.
- Dissolve the instant espresso powder in 1 tablespoon boiling water and add it while still hot to the processor, pulsing to blend into the buttercream.
- If you are doing this by hand, sieve the icing sugar and beat it into the butter with a wooden spoon.
- Then beat in the hot coffee liquid.
- Place 1 sponge upside down on your cake stand or serving plate.
- Spread with about half the icing; then place on it the second sponge, right side up (i.e. so the 2 flat sides of the sponges meet in the middle) and cover the top with the remaining icing in a ramshackle swirly pattern.
- This cake is all about old-fashioned, rustic charm, so don’t worry unduly: however the frosting goes on is fine. similarly, don’t fret about some buttercream oozing out around the middle: that’s what makes it look so inviting.
- Gently press the walnut halves into the top of the icing all around the edge of the circle about 1cm apart.